Infrared (IR) thermometers measure the IR radiation from bodies and output a temperature corresponding to the intensity of radiation measured within the frequency range of the IR thermometer. IR thermometers are calibrated by sensing the radiation from a thermal target heated to a precisely known temperature. The radiance measured by the IR thermometer may then be mapped to the set temperature of the target.
The accuracy of thermal targets is limited by changes in the emissivity of the target with temperature. The emissivity of the target also varies with the wavelength of radiation incident on and reflected from the target. However, the IR thermometer being calibrated may have an emissivity setting that is less than one, such that the IR thermometer may be used to measure the temperatures of bodies having low emissivities. However, the emissivity setting is typically constant and is therefore not equal to the emissivity of the target across a range of temperatures. Accordingly, the IR thermometer may not be accurately calibrated for all temperatures within a needed range.
In view of the foregoing, it would be an advancement in the art to provide a convenient system and method for accurately calibrating an IR thermometer having a constant emissivity setting using a thermal target having temperature-dependent emissivity.